Cousin Relationships Explained: First, Second, Removed, & More

Ever wonder what to call your parent's cousin or how your cousin's kid is related to yours? It's easier to understand than you might expect.

Updated April 18, 2023
Cousins posing for family portrait

Anyone who has attended a family reunion can see there are tons of different types of cousins (first cousins, second cousins, cousins by marriage, you name it). While it is possible to refer to a number of extended family members simply as "cousins," this can actually mean a lot of things.

Whether you grew up with your cousins or are meeting them for the first time, it really helps to know a bit about exactly how you're related. Use this simple cousin charts to help you better understand genealogy terms like "first cousins," "second cousins," and "first cousins once removed."

Basic Types of Cousins

In the most basic sense, a cousin is defined as any relative by marriage or blood, especially one who is more distant than a sibling but shares an ancestor with you. Clearly, this includes a pretty big group of people, so it helps to break cousin relationships down by type.

The terminology used to describe the relationship between cousins can be confusing, too. Everything has to be adjusted to reflect as many generations as needed, including third cousins, fourth cousins, and so on. These are some basic types of cousins to help you keep the terms straight.

  • First cousin - You and this person share a common grandparent.
  • Second cousins - You and this person share a common great-grandparent.
  • Third cousin - You and this person share a common great-great-grandparent (the grandparent of a grandparent).
  • Fourth cousin - You and this person share a common great-great-great-grandparent (the grandparent of a great-grandparent).
  • Cousin once removed - This person is the cousin of your parent or the child of your cousin (basically, a first cousin with one extra generation thrown in).
  • Cousin twice removed - This person is the cousin of your grandparent or the grandchild of your cousin.
  • Cousin by marriage - You and this person are cousins because of a marriage, so they could be the spouse of your cousin or your spouse's cousin.
Need to Know

Cousins can be related by blood or by marriage. To determine if your cousin is a blood relation, you'll need to know who their parents and grandparents are and whether you share any branches in your family tree. Being a "blood relation" really just means you are related by birth instead of by marriage or adoption.

Cousin Chart

What Is a First Cousin?

First cousins share a grandparent, either maternal or paternal (on your mom's side or your dad's side). The children of your uncles and aunts are your first cousins. Generally, you share both of a set of grandparents, but you can also be half-first cousins who share only one grandparent.

What Is a Second Cousin?

You and your second cousins share the same great-grandparents, either on your mom's side or your dad's side. You are descended from siblings in that family - your second cousin's grandparent is your grandparent's sibling. Understanding second cousins is much the same as understanding first cousins, except the family tree must go back one further generation.

Are Second Cousins Blood-Related?

Second cousins are blood-related because they are the children of first cousins. You share a common great-grandparent.

Can You Marry Your Second Cousin?

It is legal to marry your second cousin in all US states, but around half of states prohibit or restrict marriage between first cousins. This is because studies show that the risk of birth defects in babies born to parents who are first cousins is twice as high as babies born to unrelated parents. This risk drops off dramatically with second cousins because they share less of the same autosomal DNA. Second cousins who have children together have no more risk of having a child with a birth defect than any other unrelated couple.

Fast Fact

How much genetic material you share with your cousins varies depending on how closely you are related. Your first cousin shares 12.5% of your autosomal DNA, but your second cousin only shares 3.125%.

What Do You Call Your Parent's Cousin's Kid?

Your parent's cousin's kid is your second cousin. Your mom or dad and their mom or dad are first cousins, but you and this kid are second cousins.

What About Your Cousin's Kid and Your Kid?

Your cousin's kid and your kid are also second cousins. You and their mom or dad are first cousins, sharing grandparents. Your kid and your cousin's kid are second cousin, sharing great-grandparents.

Cousins Removed

In addition to the distinction between first cousins and second cousins, there is also the added designation of being "once removed." Being a "once removed" cousin means there is one generation separating you and your cousin. This could be one generation above yours or one generation below yours.

First Cousin Once Removed

You and your first cousins are all from the same generation, but when you talk about a different generation, you're talking about once removed. There are a couple of ways to have a first cousin that is once removed:

  • Your parent's cousin - Wondering what you call your mom or dad's cousin? This person is your first cousin once removed.
  • Your cousin's child - It can be a little confusing to know what you call your cousin's kid, but this child is your first cousin once removed as well.

Second Cousin Once Removed

To find a second cousin once removed, use the same logic. Your mom or dad's second cousin would be someone they share great-grandparents with. To have a second cousin once removed, you just need to move out two generations:

  • Your parent's second cousin - Your mom's second cousin or your dad's second cousin would be your second cousin once removed because your parents are one generation older than you.
  • Your second cousin's child - If you move down a generation, your second cousin's child would be your second cousin once removed.
Need to Know

What's the difference between a cousin being twice removed and someone being a second cousin? It's about how many generations exist between the cousins. If they are the same generation and share a great-grandparent, they are second cousins. If they are two generations apart (like this person is your Grandma's cousin), then they are cousins twice removed.

First Cousin Twice Removed

Since "removed" denotes the number of generations between you and a relative, "twice removed" means there are two generations separating you and your cousin. This could mean two generations above you or two generations below you:

  • Your grandparent's cousin - If you ever wonder what you should call your grandparent's cousin, this person is your first cousin twice removed.
  • Your cousin's grandchild - If your first cousin has a grandchild, this kid is also your first cousin twice removed.

Second Cousin Twice Removed

You can extrapolate the family tree to see how a second cousin can also be twice removed. There are two ways for this to work:

  • Your grandparent's second cousin - If your grandparent has a second cousin, this person would be your second cousin twice removed.
  • Your second cousin's grandchild - The grandkid of your second cousin would be your second cousin twice removed too.

Keep Track of Your Cousins

Track your cousins as far back as desired by starting to make a family tree. You can purchase family tree software or use a free family tree template to draw your own family tree. This can be a great way to really understand those cousin relationship, and it makes a great gift for your cousins too. After all, calling someone your first cousin or second cousin is all about naming your family connection.

Cousin Relationships Explained: First, Second, Removed, & More